Inside Health

Weak Bones Among Men Are Linked To Estrogen

By SUSAN GILBERT

Published: December 8, 1998

New research is challenging the medical textbook view of osteoporosis as largely a women's disease linked to the singularly female experience of menopause. It now seems that osteoporosis is more prevalent in men than previously thought and that, although men do not go through menopause, the main cause of the degenerative bone disorder is the same in men and women: an age-related drop in estrogen.

Several recent studies show that men's levels of this sex hormone decline with age and that the decline leads to a loss of bone mass, the signature symptom of osteoporosis. Some of these studies were presented last week at a meeting of the American Society for Bone and Mineral Research and the International Bone and Mineral Society in San Francisco.

''This is surprising,'' said Dr. B. Lawrence Riggs, a professor of medical research at the Mayo Clinic in Rochester, Minn., who has found that estrogen naturally falls in men after about age 65. ''Three years ago, none of us would have thought that estrogen loss was a factor in male osteoporosis.'' Although men and women have estrogen, it is more abundant in women and plays a central role in female reproduction.

The National Osteoporosis Foundation in Washington estimates that of the 10 million Americans who have osteoporosis, more than 1.5 million are men, and that half of women and 1 in 8 men over 50 will have an osteoporosis-related fracture. But because osteoporosis is underdiagnosed in men, the numbers for men are probably higher, the organization's literature says.

Medical textbooks describe osteoporosis differently for men than for women. In women it is linked mainly to the sharp drop in estrogen after menopause, because estrogen is known to slow down the natural process of bone loss that occurs with age. In men, however, osteoporosis is said to result from abnormally low levels of testosterone, a sex hormone more plentiful in males. The cause of low testosterone is usually a rare condition called hypogonadism, in which the testicles are underactive.

Two studies presented at last week's meeting indicate that estrogen plays a more central role than testosterone in osteoporosis in men. Researchers following residents of Framingham, Mass., over five decades studied 382 elderly white men for eight years, tracking bone density, estrogen levels and signs of hypogonadism. Men with the highest bone density also had the highest estrogen levels; the connection with hypogonadism was negligible.

In another study, doctors in Germany measured bone density as well as estrogen and testosterone levels of 300 men with osteoporosis for five years. Forty percent of the men had low estrogen; 20 percent had low testosterone.

''We didn't see a pronounced effect of testosterone on the males' bone mineral density,'' said Dr. Peter H. Kaps, an orthopedic surgeon and the lead author.

Dr. Pamela Taxel, assistant professor of medicine at the University of Connecticut Health Center in Farmington, said: ''These are suggestive findings, but larger studies are needed to understand the mechanism of estrogen and testosterone on bone health in men.''

Dr. Taxel is studying the use of estrogen supplements to treat men with osteoporosis. She said research was needed to develop a form of estrogen that helps men without causing side effects like prostate disease or impotence.

Chart: ''Ways to Keep Osteoporosis at Bay'' Men concerned with osteo-porosis should take the following steps to preserve bone health. Recognize and seek treatment for medical conditions that may affect bone density. Change unhealthy habits, like smoking, excessive alcohol intake and inactivity. Insure a daily calcium intake of 1,000 mg/day to age 65 and 1,500 mg/day over age 65. Insure adequate vitamin D intake either through exposure to 10 minutes of sunlight a day or by taking at least 400 IU but not more than 800 IU/day. Engage in regular exercises in which bone and muscles work against gravity. These include walking, jogging, racquet sports, stair climbing and team sports. Also, lifting weights appears to help preserve bone density. (Source: National Osteoporosis Foundation)